An engine cover mounting structure comprising an engine member and an engine cover, wherein a plurality of portions to be fixed to which fixing portions provided on the engine cover are mounted are provided so as to be situated below an upper surface of a cylinder head cover of the engine member. In addition, a positioning portion is provided on the engine cover. Then, in a state where a base fixing portion is mounted or temporarily mounted to a base portion to be fixed, while the other fixing portions are not mounted to the other portions to be fixed, when the engine cover revolves about the base fixing portion, so that the positioning portion is brought into abutment with a surface of the engine member, the fixing portions other than the base fixing portion are disposed at positions facing the portions to be fixed, respectively.